Gear grinder



M. MAAG GEAR GRINDER Filed Nov. 0-

May 3919 27.

ATTORNEY Patented May 3, 1927.

UNITED STATES PATENT" OFFICE.

MAX MAAG, or sonwnmnnnmenn, SWITZERLAND, nss'ronon 'ro mane GEAR WHEEL AND MACHINE COMPANY, urn, or ZURICH, SWITZERLAND, a conroaarron' or SWITZERLAND.

GEAR GRINDER.

This invention relates to a method of and machine for generating the tooth curves of gears. Particularly, the invention relates to improved means for controlling the movements of the gear blank being operated on so that it may be rolled a predetermined distance while in contact with an abrasive wheel, and indexed when out of contact therewith, the rolling action being repeated and reduced to a minimum to expedite the operation of the machine.

It is a principal object of the present invention to provide means for rolling a gear blank being operated upon in a car tooth F grinding machine through" a pre etermined distance or arc. This distance is adjusted to substantially equal the circular pitch of the particular blank being ground. Simultaneously with the rolling motion, the work spindle and blank thereon are advanced slowly relative to the wheel or wheels in a direction tangentially of the rolling circle and in the direction of the rolling motion.

It is also an object of the present invention to provide improved means to 'move the work-spindle in a direction to engage and disengage the blank from the wheel or wheels so that it may be returned to its initial position without rotative movement between the rolling movements, this return movement being such that the blank is again positioned and properly indexed for successive rolling movements.

I accomplish' the above named objects by means which include a fixedvrack mounted on the base of the machine and adapted to be engaged by a master gear on the work carrying spindle, this spindle being reciprocated while its axis always remains in paral* lel ositions. motions of the spindle are accomp ished b means of a crahk which may be adjuster. The distance through which the spindle is moved to cause rolling of the blank is made to correspond approximately with the circular pitch of the gear blank bein opprated upon: The crank which pro era ly is mounted on a slide is moved, together with its slide, in a direction parallel to the rack at a very slow speed so that successive op erations of the wheels u on the gear teeth will take place upon-di erent portions of the tooth profiles. The movement of the "slide carrying this actuating crank is adjust- Preferably the reci rocatory ed so that it is sufiicientto cause the Wheels to engage upon the entire contour of the gear teeth. For that reason this latter crank is made adjustable as to its stroke.

The means to engage and disengage the blank relative to the wheels is timed to permit the master gear to engage the rack throughout the rolling motion of the blank. As soon as this movement is completed, durmg which the blank is in effect rolled past and in contact with the wheels, the spindle and parts thereon are moved in a direction normal to the pitch plane of the rack. With the blank disengaged from the wheels and the master gear disengaged from the rack, the spindle is returned to its initial position by additional roative movements of the crank.

Successive rolling and return movements of the blank .serveto engage successive teeth of the master gear with the rack and so index the blank relative to the wheels. This indexing movement therefore presents successive teeth of the gear blank to the action of the wheels.

The advancing movement of the spindle serves to effect a feeding action of the gear blank relative to the wheels and may therefore preferabl be very slow. The crank by means of w ich this movement is accomplished is made to complete one rotative movement during the grinding of a gear so that the slide is moved forward and back once during this operation. In order that the feeding movement may be such that the rolling action may take place upon slightly different parts of the tooth profiles during the movement of the slide in opposite directions, the crank for moving the slide is ofl'set slightly from the point at which its connecting rod is attached to the slide so that each tooth will be'enga ed upon slightly difierent positions during t 1e movements of the slide in opposite directions.

With these and other objects in view, my invention consists in the features of construction and operation set forth in the following specification and illustrated in the accompanying drawing.

In the accompanying drawing annexed hereto and forming a part of this. specification, I heveshown my invention embodied in a spur gear grindin machine, but it will be understood that t e invention can be otherwise embodied and that the drawing Kill is not to be construed as defining or limiting the scope of the invention, the claimsappended to this specification being relied upon for that purpose.

In the drawing: 4 Figure 1 is a (plan view of. the rmcipal parts of a in ing machine me e in acwithout departlng from the spirit of the invention.

Briefly, my invent on 1n1ts broadest aspact comprises the following principal parts st, a base having a column thereon supporting a pair of freely swinging arms on which is mounted the work supporting and rotating spindle; second, one or more abrasive wheels adjustably supported on the base; third, a master rack fixed to the base and ada ted to engage a master gear on the work spindle; fourth, a crank for oscillating one of the arms so that the arm carrying the work spindle will be reciprocated through a. short distance, fifth, a slide carrying the crank and its driving mechanism; sixth, a small crank or other means for reciprocating the slide slowly through a small distance; and seventh, a rotary cam adapted to be actuated in timed relation to the reciproca-' tions of the crank to engage anddiseniage the master gear relative to the fixed r'ac 1n timed relation to the rolling movements of the blank.

Referring more in particular to the figures of the drawing, I prtvide a base 10 on which is mounted a column 11 at one side for supporting freely swinging arms 12 and 13. At the outer end of the arm 13 is a rotatable work spindle 14 disposed in a vertical axis, the arms 12 and 13 being such that the spindle 14 may be moved in any direction while its axis is maintained in parallel positions.

On the horizontal surface of the base 10 are mounted abrasive wheel supporting members 15 for abrasive wheels 16, two of which are preferably provided. As these wheels 16 and their supports 15 are in every way similar to those in my copending application filed on even date herewith, no further description of them is thought to be necessary. The wheels 16 are disposed as clearly shown in Fig. 1 in op osed relation to each other and are adapte to enga e work upon radially extending surfaces-wgich are dressed perfectly plane. The wheels 16 as shown engage opposite side ortions of alternate teeth but they may be a justed toward or from each other as desired. The work spindle 14 supports a rotatable work arbor 17.

In order to effect a rolling action of a gear blank mounted on the work spindle 14, I provide a fixed precision rack 18 on the base 10 and a master car 19 of the same itch diameter as the lank being operate on the work arbor 17. Also, preferably adjacent the rack 18 and master gear 19 is a plane surface 20 extending parallel to the pitch plane ofthe rack 18 and adapted to be engaged by the outer periphery of a ball bear- 111 21 mounted on the work spindle 14. It will be seen from the above description that by reciprocating the outer arm 13 while the master gear 19 and rack 18 are in engages ment, that the blank on the spindle 14 will be rolled past the abrasive wheels 16 which may be properly adjusted to engage the tooth portions thereof.

' In order to effect this reciprocatory movement,-a crank 23 is provided connected to the arm 13 by means of a short connecting rod 24. Rotation of this crank 23 as by means of the gearing shown inFig. 1 will oscillate the arm 12 and therefore reciprocate the enter one. 13 a distance determined by the stroke of the crank. Adapted to be operated in timed relation with this crank 23 is a small cam 25 bearing upon a surface of the outer arm 13. Rotation of this cam 25 alternately moves the spindle 14 with its master gear 19 in a direction normal to the pitch plane of the rack 18 so that the rack 18 and master gear 19 are disengaged, the blank being also disengaged from the abrasive wheels 16. This cam 25 may be conveniently rotated by means of the gearing shown in Fig- 1 preferably from the shaft 26 as the means for mounting the crank 23. The above.described mechanism is substantially similar to my copending application Serial No. 677,- 841 filed November 30, 1923 and the motions given the parts are substantially similar. The rolling action of the spindle 14 however in the present application is materially restricted over that in the copending application and is carefully adjusted by proper positioning of the crank 23 to correspond substantially to one circular pitch only of the blank being operated upon. As the cam 25 and crank 23 are positively driven, the truing of these parts may be precisely maintained. The cam 25 in the embodiment of the invention illustrated in the drawing is driven at the same speed as the crank 23 so that it disenga es the master gear 19 from the rack 18 once uring each rotation of the crank 23. The spindle 14 held toward the wheels 16 by means of a spring 27.

The crank 23 and cam 25 in the drawing are shown connected to rotate at. the same Ian speed so that after each rolling movement of the blank in one direction, the cam 25 withdraws the blank from the wheels 16 and permits it to be returned to its initial position. It will be understood, however, that the timed relation between the cam 25 and crank 23 may be 1:3, 1: 5, or so ,forth. In this case, the blank instead of being rolled past the wheels once 'between its return movement without rollin will be rolled three or five times res ectively. When this rolling motion is comp eted depending upon the timing of the cam 25, the blank is with drawn from the wheels and indexed by being returned to its initial position without rolling.

It will be noted that the crank 23 for reciprocating the outer arm together with its driving mechanism is mounted upon a slide 28 movable parallelly of the pitch plane of the rack 18. This slide 28 is adapted to be very slowly moved'by the provision of a secondary or auxiliary crank 29 the axis about which it rotates being fixed in the base 10: This secondary crank 29 is adapted to be rotated very slowly by means of the worm and worm wheel as shown in Fig. 1 and is attached to slide 28 by rod 30. This crank 29 is also preferably made adjustable so that it is rotated to gradually move the slide and its attached parts in one direction and then in a return direction through a predetermined distance. One complete rotation of the secondary crank 29 is designed to take place while the main crank 23 is rotated and the blank being operated on is rolled sufficiently to cover the entire number of teeth a plurality of times.

With the rolling movement of the blank and the master gear 19 restricted substantially to one circular pitch of the blank, it will be noted that successive rolling movements of the blank without movement of the auxiliary crank 29 to advance the slide 28 will cause the wheels 16 to engage a small part only of the active profiles of the teeth. These teeth will therefore be abraded over a small portion of their profiles throughout the circumference of the gear, and, during one complete rotation of the blank, the secondary .crank is rotated through a small angular distance. When the blank therefore is being rotated a second time, the abrasive action of the wheels 16 will take place upon adjacent portions of the tooth profiles. The movement of the crank 29 is adjusted so that the advancing action of the slide 28 is sufiicient to cause the blank to be abraded throughout'the entire profile of its teeth.

Preferably, the crank 23 is adjusted so that the rolling movement of the blank is slightly eater than the circular pitch of the gear ing ground. This is for the urpose of eliminating any errors due to ck lash or lost motion between the fixed rack 18 and master gear 19. The amount of rolling movement of the blank is increased an amount equal to the maximum movement of slide 28 between the indexing return movement of the blank. With the rolling movement so increased the master gear 19 when it reengages the rack will come into mesh with the driven sides of its teeth in contact with the driving sides of the teeth on the rack. In this way, the wheels 16 engage the teeth of the blank when all lost motion is held always on the same side.

Preferably, and as shown in Fig. 1, the crank 23 is slightly offset from the point at which its connecting rod 24. is attached to the arm 13. This provides a slightly irregular reciprocation of the arm 13. The cam 25 is so positioned .that the slower portion of the arm 13 reciprocation takes place during the abrading operation and the quicker or return movement takes place while the cam 25 holds the spindle and parts attached thereto away from the wheels.

Also the crank 29 is similarly offset from the point its connecting rod 30 is attached to the slide 28. By this means the movement of the slide 28 in its opposite direction causes the wheels 16 to engage slightly different portions of the tooth profiles. The profiles therefore will be more smoothly finished than if the wheels 16 engaged exactly the same' portions of the tooth profiles while the blank completes its advancing and returning movements.

What I claim is:

1. The method of grinding the tooth curves of a car comprising rolling a blank past a grinding wheel through a distance substantially equal to its circular pitch, withdrawing said gear ,from contact with said wheel. indexing said gear between successive rolling and withdrawing motions, returning said gear to engage said wheel, and continuing said rolling and indexing motions in timed relation to each other while the gear is being advanced in the direction of the rolling motion.

2. The method of grinding the tooth curves of a gear comprising rolling a blank past a grinding wheel through a distance substantially equal to its circular pitch, withdrawing said blank from engagement with said wheel, returning the blank to its initial position without rolling, and continulng said rolling and returning motions in timed relation to each other while the gear is being moved in the direction of the rolling motion.

3. The method of grinding the tooth til) curves of a gear comprising rolling a blank blank.

continuing said rolling and returnin motions while the blank is being moved 1n opposite directions parallel to the rolling motion through a sufiicient distance to completely generate the tooth curves of the 4. A gear tooth grinding machine comprising in combination, a base, an abrasive wheel mounted thereon, a work supporting spindle on said base adapted to be moved in any direction while its axis remains vertical, interengaging means on said base and spindle whereby a gear blank on said spindle may be rolled predetermined distances in engagement with said wheel, and means to slowly advance the position through which the blank is rolled to cause the wheel to engage the wheel with a tooth curve over its entire profile.

5. A gear tooth grinding machine comprising in combination, a base, an abrasive wheel mounted thereon, a work supporting spindle on said base adapted to be moved in any direction while its axis remains Vertical, interengaging means on said base and slowly advance the position through which.

the blank is rolled to cause the wheel to engage the wheel with a tooth curve over its,

entire profile.

6. A gear tooth inding machine comprising in combination, a base, an abrasive wheel mounted thereon, a work supporting spindle on said base adapted to be moved in any direction while its axis remains vertical, interengaging means on said base and spindle whereby a gear blank on said spindle may be rolled predetermined distances in engagement with said wheel, means to adjust the distance through which the gear is rolled, and means to slowly advance the position throu h which the blank is rolled to cause the w eel to engage the wheel with a tooth curve over its entire profile.

7. A gear tooth grinding machine comprising in combination, a base, an abrasive wheel mounted thereon, a work supporting spindle on said base adapted to be moved in any direction while its axis remains'vertical, interengaging means on said base and spindle whereby-a gear blank on said spindle may be rolled a distance equal to its circular pitch while in engagement with said wheel, and means to slowly advance the position through which the blank isrolled tangentially in the direction of the rolling'movement to cause the wheel to engage the wheel with a tooth curve over'its entire profile. I v

In testimony whereof, I hereto afix my signature. 7

MAX MAAG. 

